package nc;

import java.text.DecimalFormat;
import java.util.Scanner;

public class Q21330 {

    public static double getCubeRoot(double input) {
        // 牛顿快速计算法
        double e = 0.00001;
        double i = 1.0;
        while (!(Math.abs(i * i * i - input) < e)) {
            i = next(i, input);
        }
        return i;
    }

    public static double next(double last, double input) {
        return (2 * last / 3.0 +input / (3.0 * last * last));
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        DecimalFormat format = new DecimalFormat("0.0");
        while (scanner.hasNext()) {
            System.out.println(format.format(getCubeRoot(scanner.nextDouble())));
        }
    }

}
